The invention relates to a two-axis inclinometer for measuring inclinations or changes in inclination in two mutually perpendicular directions.
Two-axis inclinometers are used, for example, in geodesy for leveling geodetic measuring instruments. In such inclinometers, an element is provided which changes its position as a function of gravity. A measuring mark is projected above the element onto a positionally stable receiver. A positional variation arising here with respect to a previously adjusted zero point is a measure of the inclination of the instrument.
Such an inclinometer is known from EP 0 161 207 B1. Using slit illumination, a light bundle is projected via a mirror onto a combined glass-liquid prism. The prism has a container filled with silicone oil, the inclination being determined via a reflection at the liquid horizon and projection of the ray onto a light-sensitive array. It is possible to determine only a uniaxial direction of inclination in conjunction with a restricted measurement range using the slit illumination described in the above reference. However, biaxial inclination measurements are necessary with geodetic instruments, in particular.